This invention relates generally to the field of electronic devices and systems, and more specifically to optical switching technology.
A relay or switch may be used to change an optical signal from a first state to a second state. In general there may be more than two states. In applications that require a small switch geometry or a large number of switches within a small region, microelectronic fabrication techniques may be used to create switches with a small footprint. A microelectronic switch may be used in a variety of applications, such as industrial equipment, telecommunications equipment and control of electromechanical devices such as ink jet printers.
In switching applications, the use of piezoelectric technology may be used to actuate a switch. Piezoelectric materials have several unique characteristics. A piezoelectric material can be made to expand or contract in response to an applied voltage. This is known as the indirect piezoelectric effect. The amount of expansion or contraction, the force generated by the expansion or contraction, and the amount of time between successive contractions are important factors that influence the selection of a piezoelectric material in a particular application. Piezoelectric material also exhibits a direct piezoelectric effect, in which an electric field is generated in response to an applied force. This electric field may be converted to a voltage if contacts are properly coupled to the piezoelectric material. The indirect piezoelectric effect is useful in making or breaking a contact within a switching element, while the direct piezoelectric effect is useful in generating a switching signal in response to an applied force.
A method and structure for an optical switch is disclosed. According to a structure of the present invention, a gas-filled chamber is housed within a solid material. The solid material may be composed of glass, ceramic, metals and adhesive material. A plurality of contacts within the gas-filled chamber are coupled to the solid material, while a plurality of piezoelectric elements within the gas-filled chamber are also coupled to the solid material. A slug within the gas-filled chamber is coupled to one or more of the plurality of contacts and further coupled to one or more of the plurality of piezoelectric elements. The slug is operable to move within the chamber and make or break connections with one or more of the plurality of contacts. A liquid metal within the gas-filled chamber is coupled to the slug, and coupled to the plurality of contacts. The liquid metal acts as a friction-reducing lubricant for motion of the slug, and also is operable to provide a surface tension that maintains a connection between the slug and a contact of the plurality of contacts. According to a method of the present invention, one or more of the plurality of piezoelectric elements are actuated, with the actuation of the one or more piezoelectric elements causing the slug coupled to the one or more piezoelectric elements to move from a first number of contacts to a second number of contacts. The first number of contacts and the second number of contacts are wetted by the liquid metal. The movement of the slug from the first number of contacts to the second number of contacts breaks a liquid metal surface tension between the slug and the first number of contacts and establishes a coupling between the slug and the second number of contacts, thereby enabling the liquid metal switch to change from a first state to a second state. The surface tension of the liquid metal between the slug and the second number of contacts is then operable to maintain a coupling between the second number of contacts and the slug.